Seal arrangement for a motor pump assembly

ABSTRACT

An electric machine includes an end frame having a shaft bore extending therethrough. The end frame includes a first side and a second side. A shaft extends through the shaft bore. A bearing is supported by the end frame and is coupled to the shaft to support the shaft for rotation about a longitudinal axis. A first seal is fixedly attached to the end frame and includes an internal bore that is sized to cooperate with the shaft to form a seal point therebetween. The first seal is disposed on the first side of the end frame. A second seal is fixedly attached to the second side of the end frame. The second seal includes a movable portion in direct contact with the shaft to define a second seal point. The first seal point is on a first side of the bearing and the second seal point is on a second side of the bearing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/790,821 filed Mar. 8, 2013, the entire content of which isincorporated herein by reference.

BACKGROUND

The present invention relates to a multi-seal arrangement for anelectric motor. The multi-seal arrangement inhibits the passage ofparticles or liquids from being introduced to a bearing of the electricmotor.

SUMMARY

In one embodiment, the invention provides an electric machine. Theelectric machine includes an end frame having a shaft bore extendingtherethrough. The end frame includes a first side and a second side. Ashaft extends through the shaft bore. A bearing is supported by the endframe and is coupled to the shaft to support the shaft for rotationabout a longitudinal axis. A first seal is fixedly attached to the endframe and includes an internal bore that is sized to cooperate with theshaft to form a seal point therebetween. The first seal is disposed onthe first side of the end frame. A second seal is fixedly attached tothe second side of the end frame. The second seal includes a movableportion in direct contact with the shaft to define a second seal point.The first seal point is on a first side of the bearing and the secondseal point is on a second side of the bearing.

In another embodiment the invention provides an electric machine. Theelectric machine includes an end frame having a shaft bore extendingtherethrough. The end frame includes a first side internal to theelectric machine and a second side external to the electric machine. Ashaft extends through the shaft bore and is rotatable about an axis. Abearing is supported by the end frame and rotatably couples the shaft tothe end frame for rotation about the axis. A first seal assembly isdisposed around the shaft on the first side of the end frame. The firstseal assembly is in non-contact with the shaft and the end frame. Asecond seal assembly is disposed around the shaft on the second side ofthe end frame. The second seal member is in direct contact with theshaft and the end frame.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a motor pump assembly.

FIG. 2 is a perspective view of a rotating assembly and end frame of anelectric motor of the motor pump assembly of FIG. 1.

FIG. 3 is a front cross section of an end frame of the electric motor ofFIG. 1 along section lines 2-2.

FIG. 4 is a perspective view of a cross section of the electric motor ofFIG. 1 along section lines 2-2.

FIG. 5 is an exploded view of the rotating assembly and end frame of theelectric motor of FIG. 1.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways.

FIG. 1 schematically illustrates a motor-pump assembly 4 suitable foruse in pumping fluids such as water refrigerant, or other liquids. Themotor-pump assembly 4 includes a pump 5 that is directly connected to amotor 8. In most constructions, a coupling element (not shown) ispositioned between the motor 8 and the pump 5 to allow for disconnectionof the two components. In addition, some constructions may employ atransmission or other speed changing device between the motor 8 and thepump 5 to allow the pump 5 to rotate at a speed different from the motor8.

The pump 5 includes an inlet 6, an outlet 7, and a rotating element 9 influid communication with the inlet 6 and the outlet 7. Rotation of therotating element 9 draws fluid into the pump 5 via the inlet 6 anddischarges the fluid via the outlet 7. The motor 8 is typically an ACpowered electric motor such as an open drip proof electric motor that iscoupled to the rotating element 9 of the pump. The motor 8 includes ahousing 11 and a stator 13 disposed within the housing 11 and fixed withrespect to the pump. The stator 13 includes an opening 15 sized toreceive a portion of a rotating assembly 10 and is operable to produce amagnetic field that interacts with a magnetic field of the rotatingassembly 10 to rotate the rotating assembly 10 and drive the rotatingelement 9 of the pump 5.

FIG. 2 illustrates the rotating assembly 10 of the electric motor 8. Therotating assembly 10 attaches to and is at least partially supported forrotation by an end frame 14 that attaches to the housing 11. Therotating assembly 10 includes a fan 18, a rotor 22, and a first bearing26 disposed about a shaft 30. The fan 18 is fixedly coupled to the shaft30 adjacent the end frame 14 so that the fan 18 rotates with the shaft30 and provides cooling of the electric motor 8. In other motors, othertypes of fans or other fan arrangements may be employed. In some motors,the fan may be omitted entirely.

The shaft 30, best illustrated in FIG. 5, is an elongated substantiallycylindrical member 32 that provides rotational support to the rotatingcomponents of the motor 8. In the illustrated construction, the shaft 30extends along a longitudinal axis 34 and includes a first diameterportion 38, a second diameter portion 42, and a third diameter portion46. The shaft 30 includes an outer surface 50 having threecircumferential grooves 54.

A rotor 22 is fixedly supported by the shaft 30 and is rotatable withthe shaft 30 and the fan 18 relative to a stator 13. The rotor 22 andthe stator 13 can be virtually any arrangement of rotor 22 and stator 13without effecting the operation of the invention. For example, brushedor brushless DC rotor and stator arrangements or AC rotor and statorarrangements could be employed with the invention described herein. Themotor-pump assembly 4 can be applied vertically or horizontally withpreferred arrangements being horizontal.

The first bearing 26, illustrated in FIGS. 2 and 5, includes an innerrace 58 that is coupled to the shaft 30 for co-rotation, an outer race62 that engages the motor housing 11 or a second end frame that attachesto the housing 11, and a plurality of rolling-elements 66 thatfacilitate the relative rotation between the inner race 58 and the outerrace 62. As illustrated in FIG. 2, the rolling-elements 66 are balls andthe first bearing 26 is a common ball bearing. In other constructions,other types of bearings such as roller bearings, needle bearings, sealedbearings, and the like may be employed.

As illustrated in FIGS. 4 and 5, the rotating assembly 10 also includesa second bearing 70 disposed within the end frame 14 as will bediscussed below. The second bearing 70 is similar to the first bearing26 and includes an inner race 74 that is coupled to the shaft 30 forco-rotation, an outer race 78 that engages the end frame 14, and aplurality of rolling-elements 82 that facilitate the relative rotationbetween the inner race 74 and the outer race 78. As illustrated in FIG.4, the rolling-elements 82 are balls and the second bearing 70 is acommon ball bearing. In other constructions, other types of bearingssuch as roller bearings, needle bearings, sealed bearings, and the likemay be employed.

Referring to FIG. 3, the end frame 14 is generally made of cast aluminumbut may be any type of material suitable for use with motors. The endframe 14 includes an inner, generally planar wall face 86 and an outer,generally planer, wall face 90. The inner wall face 86 is disposed onand faces an inside 94 of the electric motor 8, and the outer wall face90 is disposed on and faces an outside 98 of the electric motor 8. Asshown in FIG. 3, the end frame 14 further includes a generallycylindrical bearing cavity 102 which extends inward into the end frame14 and surrounds the longitudinal axis 34. The bearing cavity 102includes an annular shoulder 106 thereby defining a bearing seat 110located within the end frame 14. A first annular surface 114 is definedat one end of the bearing cavity 102 and extends perpendicular to thelongitudinal axis 34. Two apertures 118 extend from the first annularsurface 114 through the end frame 14 parallel to the longitudinal axis34. A plurality of flanges 122, shown in FIG. 5, extend outwardly fromthe end frame 14 and define holes 126 through which bolts or screws (notshown) may extend to couple the end frame 14 to the motor housing 11.

The end frame 14 also includes a cylindrical shaft bore 130 that extendsthrough the end frame 14 and extends around the longitudinal axis 34.The shaft bore 130 is sized to allow the shaft 30 to extend through theshaft bore 130. The shaft bore 130 is sized such that the shaft 30 doesnot come into contact with a cylindrical surface 134 of the bore 130which closely surrounds the rotatable shaft 30. The shaft outer surface50 and the cylindrical surface 134 of the bore 130 are slightly spacedapart so as to permit free relative rotation therebetween.

The end frame 14 also includes a recessed portion 138 disposed on theoutside 98 of the end frame 14 which extends inward into the end frame14 and surrounds the shaft bore 130. The recessed portion 138 ispreferably a cylindrically shaped stepped recess which surrounds theaxis 34.

With reference to FIGS. 4 and 5, a snap ring 142 is coupled to the shaft30 adjacent the second bearing 70 to inhibit axial movement of thesecond bearing 70 in a first direction. The snap ring 142 is partiallyrecessed within one of the circumferential grooves 54 on the shaft 30. AC-clip assembly 146 is disposed about the shaft 30 adjacent the secondbearing 70 to inhibit axial movement of the second bearing 70 in asecond direction. The C-clip assembly 146 includes a C-clip 150 disposedbetween a pair of circular plates 154. The C-clip assembly 146 iscoupled to the shaft 30 and is partially recessed within another one ofthe circumferential grooves 54 on the shaft 30.

As shown in FIGS. 4 and 5, the end frame 14 supports three sealassemblies. A first seal assembly 157 includes a first annular disk 158disposed about the shaft 30 adjacent the end frame 14. The first annulardisk 158 includes a bore aperture 162 through which the shaft 30extends. The bore aperture 162 has a diameter 166 that is greater thanany of the diameter portions 38, 42, 46 of the shaft 30 such that thefirst annular disk 158 does not contact the shaft 30. The first annulardisk 158 abuts the first annular surface 114 of the end frame 14 and theouter race 78 of the second bearing 70 to form a seal to inhibitparticles or liquid from reaching the second bearing 70. The firstannular disk 158 includes a pair of flanges 164 extending radiallyoutwardly. The flanges 170 each include a through hole 174. In theillustrated embodiment, the first annular disk 158 is made of rubber,but may be made of an alternate resilient material.

The first seal assembly 157 also includes a bearing lock plate 178disposed around the shaft 30 on the inside 94 of the end frame 14. Thebearing lock plate 178 is in direct contact with the first annular disk158 and includes a bore aperture 182 through which the shaft 30 extends.The bore aperture 186 has a diameter 190 that is greater than any of thediameter portions 38, 42, 46 of the shaft 30 such that the bearing lockplate 178 does not contact the shaft 30. The bearing lock plate 178includes a pair of flanges 194 extending radially outwardly andpositioned to align with the flanges 164 of the first annular disk 158.The flanges 194 each include a threaded hole 198 that are each inalignment with the through holes 174 of the first annular disk 158.

The first seal assembly 157 also includes a second annular disk 202disposed about the shaft 30 adjacent to the bearing lock plate 178 onthe inside 94 of the end frame 14. The second annular disk 190 iscoupled to the bearing lock plate 170 with an adhesive with alternativeattachment means being possible. The second annular disk 190 includes abore aperture 206 sized for receiving the shaft 30. The bore aperture206 has a diameter 210 greater than any of the diameter portions 38, 42,46 of the shaft 30 and smaller than the diameter 166 of the firstannular disk 158. In preferred arrangements, the diameter 210 isslightly larger than the shaft (e.g., 0.005-0.020 inches). Thus, thesecond annular disk 202 cooperates with the shaft 30 to form anon-contact seal. A lubricant (not shown) is place on the shaft 30between the shaft 30 and the second annular disk 202 to enhance theseal. The non-contact seal inhibits particles or liquid from reachingthe second bearing 70 from the inside 94 of the end frame 14. In theillustrated embodiment, the second annular disk 202 is made of rubber,but may be made of an alternate resilient material. The second annulardisk 202 includes a pair of flanges 214 that extend radially outwardly.The flanges 214 each include a through hole 216 that are each inalignment with the through holes 174 of the first annular disk 158 andthe threaded holes 198 of the bearing lock plate 178.

As shown in FIG. 4, a second seal assembly 217 includes a radial shaftseal, or lip seal 218, coupled to the outside 98 of the end frame 14 andrecessed in the recessed portion 138 of the end frame 14. The lip seal218 includes an inner surface 222 and an outer surface 226 (FIG. 5). Theouter surface 226 is in direct contact with the end frame 14. The innersurface 222 includes a movable portion in direct contact with the shaft30 to form a seal. A biasing member such as a spring 223 positioned tobias the inner surface 222 into contact with the shaft 30. In theillustrated embodiment, the lip seal 218 is made of rubber, but may bemade of an alternate resilient material. The lip seal 218 inhibitsparticles or liquid from reaching the second bearing 70 from the outside98 of the end frame 14.

A third seal assembly 230 is positioned on the outside 98 of the endframe 14 and is positioned adjacent the lip seal 218. The third sealassembly 230 includes a first disk 234, a second disk 238, and a thirddisk 242 as shown in FIG. 4. The first disk 234 and second disk 238include an inner surface 246 and an outer surface 250. The innersurfaces 246 are fixedly attached to the shaft 30. The third disk 242 isdisposed between the first disk 234 and second disk 238 and includes aninner surface 254 and an outer surface 258. The outer surface 258 of thethird disk 242 is fixedly attached to the end frame 14 and does notcontact the shaft 30. The third seal assembly 230 inhibits particles orliquid from reaching the lip seal 218, and ultimately from reaching thesecond bearing 70, from the outside 98 of the end frame 14.

To assemble the electric machine, the shaft 30, the rotor 22, and thefan 18 are fixedly coupled to one another for co-rotation. Many optionsare available to connect the rotor 22 and the fan 18 to the shaft 30including shrink fits, keys and slots, splines, welding, brazing,soldering, adhesives, etc. The method selected for attaching the rotor22 and the fan 18 to the shaft 30 is not critical to the operation ofthe invention. The first seal assembly 157, including the first annulardisk 158, the bearing lock plate 178, and the second annular disk 202are slid over the shaft 30 to a position between the second bearing 70position and the fan 18. In preferred constructions, the first annulardisk 158 and the second annular disk 202 are adhesively bonded to thebearing lock plate 178. The C-clip assembly 146 is coupled to the shaft30 in the innermost groove 54 adjacent the location of the secondbearing 70. The second bearing 70 is then slid (or pressed) onto theshaft 30 and the snap ring 142 is placed in the outermost groove 54 tofix the axial position of the second bearing 70 on the shaft 30. The endframe 14 is placed over the bearing 70 such that the outer race 78 ofthe bearing 70 engages the annular shoulder 106. The first seal assembly157 attaches to the end frame 14 such that the first annular disk 158 isin contact with the first annular surface 114. The bearing lock plate178 is positioned in contact with the first annular disk 158 such thatfasteners 262 can pass through the first annular disk 158 and engage thethreaded holes 198 in the bearing lock plate 178. As the fasteners 262are tightened, the bearing lock plate 178 is pulled toward the firstannular surface 114, thereby compressing the first annular disk 158between the bearing lock plate 178 and the end frame 14 to improve theseal therebetween. The second annular disk 202 attaches via an adhesiveor other suitable attachment means to the bearing lock plate 178 tocomplete the assembly of the first seal assembly 157 on the inside 94the end frame 14 and on the inside of the bearing 70. Thus, the firstseal assembly 157 encloses a space around an inside of the secondbearing 70. As discussed, the first seal assembly 157 effectivelyinhibits the entry of unwanted material into the second bearing 70 fromthe inside 94 of the end frame 14. The second seal assembly 217,including the lip seal 218 is inserted into the space between the endframe 14 and the shaft 30 such that the movable portion contacts theshaft 30 and forms a seal. The third seal assembly 230 is assembledoutside of the second seal assembly 217 to complete the assembly of theelectric motor 8. Thus, the second seal assembly 217 and the third sealassembly 230 enclose a space around the outside of the second bearing70. While the assembly is described in a particular order, othercomponent arrangements may be considered.

In operation, the rotor 22 and the stator cooperate as is well known inthe art to produce rotation of the shaft 30. The first bearing 26 andthe second bearing 70 support the shaft 30, the fan 18, and the rotor 22for the desired rotation. During operation, the outside 98 of the motor8 can be exposed to debris such as water, dirt, dust, etc. The thirdseal assembly 230 provides a first barrier of entry for this debris. Thearrangement of the third seal assembly 230 makes the passage of debrismore unlikely. However, should debris pass through the third sealassembly 230, the debris is inhibited from further passage by the secondseal assembly 217. The second seal assembly 217 is in direct contactwith the end frame 14 and the shaft 30 such that the passage of debrisis very difficult. Should debris pass the second seal assembly 217, itmust still pass through the small opening between the end frame 14 andthe shaft 30 adjacent the second seal assembly 217. Thus, the secondseal assembly 217 and the third seal assembly 230 cooperate to inhibitthe entry of debris into the second bearing 70 from the outside 98 ofthe end frame 14. The first seal assembly 157 is positioned to inhibitthe entry of debris into the second bearing 70 from the inside 94 of theend frame 14. The first annular disk 158 of the first seal assembly 157forms a seal between the bearing lock plate 178 and the end frame 14 viathe compression provided by the bearing lock plate 178. In addition, thesecond annular disk 202 is sealingly coupled to the bearing lock plate178 to inhibit the entry of debris around the interfaces provided by thebearing lock plate 178 and the second annular disk 202. The boreaperture 190 of the second annular disk 202 is sized to provide a smallopening between the shaft 30 and the second annular disk 202. The sizeof the opening is small enough to inhibit the entry of debris. Inaddition, any lubricant on the shaft 30 cooperates with the secondannular disk 202 to effectively limit the size of the gap. Thus, therotating assembly 10 includes three seal assemblies 157, 217, 230 thatcooperate to seal the space in which the second bearing 70 is disposedto protect the second bearing 70 from unwanted debris.

Various features and advantages of the invention are set forth in thefollowing claims.

What is claimed is:
 1. An electric machine comprising: an end framehaving a shaft bore extending therethrough; a shaft extending throughthe shaft bore; a bearing supported by the end frame and coupled to theshaft to support the shaft for rotation about a longitudinal axis, thebearing defining a first side and a second side; a first seal assemblyfixedly attached to the end frame and including an internal bore that issized to cooperate with the shaft to form a seal point therebetween, thefirst seal assembly disposed on the first side of the bearing; and asecond seal assembly fixedly attached to the end frame, the second sealassembly including a movable portion in direct contact with the shaft todefine a second seal point, wherein the second seal assembly is on thesecond side of the bearing, wherein the first seal assembly includes afirst seal member in direct contact with the end frame and the bearing,a bearing lock plate in direct contact with the first seal member, and asecond seal member in direct contact with the bearing lock plate andincluding the internal bore.
 2. The electric machine of claim 1, whereinthe bearing includes an outer race in contact with the end frame and aninner race in contact with the shaft, and wherein the first sealassembly is in direct contact with the outer race.
 3. The electricmachine of claim 1, wherein the first seal member and the second sealmember are formed from a resilient material.
 4. The electric machine ofclaim 3, wherein the first seal member and the second seal member areadhesively bonded to the bearing lock plate.
 5. The electric machine ofclaim 1, further comprising a fastener that threadably engages thebearing lock plate to fixedly attach the first seal member and thesecond seal member to the end frame.
 6. The electric machine of claim 1,wherein the internal bore and the shaft are sized to define an annularspace therebetween, and wherein a layer of lubricant is positioned onthe shaft adjacent the internal bore, the lubricant cooperating with thesecond seal member to seal the annular space.
 7. The electric machine ofclaim 1, wherein the second seal assembly includes a lip seal having alip that contacts the shaft and a biasing element coupled to the lip tobias the lip into contact with the shaft.
 8. The electric machine ofclaim 1, further comprising a third seal assembly coupled to the endframe and positioned such that the second seal assembly is between thethird seal assembly and the bearing.
 9. The electric machine of claim 8,wherein the third seal assembly includes a first disk fixedly attachedto the shaft, a second disk fixedly attached to the shaft, and a thirddisk fixedly attached to the end frame and positioned between the firstdisk and the second disk.
 10. The electric machine of claim 1, whereinthe end frame includes a plurality of apertures positioned on a lowerside of the end frame such that the electric machine is an open dripproof motor.
 11. A pumping apparatus comprising: a pump including aninlet, an outlet, and a rotating element in fluid communication with theinlet and the outlet; a motor coupled to the rotating element in adriving relationship to rotate the rotating element, the motorincluding, a stator fixed with respect to the pump; a rotor positionedadjacent the stator and operable to rotate in response to theapplication of an electric current to the motor; a shaft coupled to therotor to support the rotor for rotation and coupled to the pump torotate the rotating element; an end frame positioned between the rotorand the pump and fixedly attached to the stator; a bearing coupled tothe end frame and the shaft to support the shaft for rotation, thebearing defining a first side between the bearing and the rotor and asecond side between the bearing and the pump; a first seal assemblycoupled to the end frame and positioned between the bearing and therotor, the first seal assembly cooperating with the shaft and the endframe to substantially enclose the first side of the bearing; a secondseal assembly coupled to the end frame and positioned between the firstbearing and the pump, the second seal assembly in direct contact withthe shaft and the end frame to substantially enclose the second side ofthe bearing; and a third seal assembly coupled to the end frame andpositioned between the second seal assembly and the pump, wherein thefirst seal assembly includes a first seal member in direct contact withthe end frame and the bearing, a bearing lock plate in direct contactwith the first seal member, and a second seal member in direct contactwith the bearing lock plate and including an internal bore.
 12. Thepumping apparatus of claim 11, wherein the first seal member and thesecond seal member are formed from a resilient material and areadhesively bonded to the bearing lock plate.
 13. The pumping apparatusof claim 11, wherein the internal bore and the shaft are sized to definean annular space therebetween, and wherein a layer of lubricant ispositioned on the shaft adjacent the internal bore, the lubricantcooperating with the second seal member to seal the annular space. 14.The pumping apparatus of claim 11, wherein the second seal assemblyincludes a lip seal having a lip that contacts the shaft and a biasingelement coupled to the lip to bias the lip into contact with the shaft.15. The pumping apparatus of claim 11, wherein the third seal assemblyincludes a first disk fixedly attached to the shaft, a second diskfixedly attached to the shaft, and a third disk fixedly attached to theend frame and positioned between the first disk and the second disk.